In a conventional ultrasonic probe, for example, a short-axis oscillating ultrasonic probe, as shown in FIG. 13, a piezoelectric element group 2 arranged along a long-axis direction and having an acoustic lens 6, is provided on a horizontal part of a rotary holding table 1 and housed in a hermetically sealed container 3 including a container body 3a and a cover 3b, which each have a concave shape in cross-section. Bearings are respectively provided in legs 1a and 1b at opposite ends of the rotary holding table 1, so as to slidingly fit with central rotation shafts 7 provided on opposite side walls of the container body 3a in the long-axis direction.
A first bevel gear 4a provided at one leg 1b of the rotary holding table 1, which rotates and oscillates in the short-axis direction, is meshed with a second bevel gear 4b firmly fixed to a rotation shaft 8 sealing and penetrating a bottom wall of the hermetically sealed container 3. Accordingly, the rotary holding table 1 and the piezoelectric element group 2 are rotated and oscillated in the short-axis direction, so that ultrasonic waves transmitted and received to/from an ultrasonic wave transmitting/receiving surface of the piezoelectric element group 2 are mechanically scanned in the short-axis direction of the piezoelectric element group 2. Liquid L, serving as an ultrasonic wave medium, for example oil, is filled in the hermetically sealed container 3.
The acoustic lens 6 here has legs 6a extending from outer peripheries of a curvature portion thereof. Furthermore projecting portions 6b serving as ultrasonic wave absorbing means, are provided on the ultrasonic wave transmitting/receiving surface side at the opposite ends in the long-axis direction. Tip sides of the projecting portions 6b have a circular arc shape following an inner periphery 3c of the cover 3b. Moreover a light-weight body 10 having a hollow portion is firmly fixed to the bottom wall of the container body 3a by an adhesive or the like, and immersed in the ultrasonic wave medium L filled in below the rotary holding table 1.
According to such a configuration, because the projecting portions 6b serving as the ultrasonic wave absorbing means are provided on opposite end sides of the acoustic lens 6, unnecessary ultrasonic waves propagating in the long-axis direction of the piezoelectric element group 2 are absorbed by the ultrasonic wave absorbing means (projecting portions 6b).